Mechanical thrombectomy device

ABSTRACT

A medical device for removing a thrombus from a blood vessel and a process thereof is presented. The device comprises an outer sheath with a plurality of lumens. A wire guide inserted through one of the lumens is used to place the device proximate to a thrombus. A chemical lysin agent is used to at least partially lyse the thrombus. A wire basket extended through the first lumen proximate to the thrombus is translated back and forth to generate a force that may be transmitted to the partially lysed thrombus assisting in the formation of smaller fragments. A vacuum coupled to the distal end of the second lumen is used to remove the lysed thrombus fragments.

FIELD

This invention relates to medical devices, and more particularly, todevices used to remove thrombus or soft tissue clots from vascular orother lumens.

BACKGROUND

Vascular disease affects a large proportion of individuals each year.One indication of the existence of this disease is the development of ablood clot in the vascular system, which if left untreated may result indeep venous thrombosis, embolisms, or ischemia. These clots, which mayeither partially or fully occlude a vessel, are usually comprised of anaggregated mixture of thrombus and fibrin.

Various known techniques for the removal of blood clots include bothchemical and mechanical treatment. Chemical treatment typically involvesthe injection of lysin agents into the vessel near the blood clot tochemically attack, dissolve, and disperse the occlusion. In thistechnique, the lysin agent is brought into the proximate vicinity of theblood clot via injection through a cannula or other lumen.

The mechanical treatment of a blood clot typically involves the use ofcatheters having a rotary cutting head or other form of a rotor/statorhomogenizing head. Examples of such rotary devices include rotating burrdevices, rotating a helical coil wire within a catheter, andrecanalization catheters. Other mechanical devices utilize a sharp pointto methodically pummel the occlusion in order to form a hole through it.In each of these cases, although the occlusion is reduced in size or apassageway is created, the residual thrombus/fibrin material resultingfrom the treatment remains within the vessel.

The removal of residual material formed during the fragmentation of ablood clot is medically desirable. It is further necessary to insurethat this residual material does not migrate away from the site of thetreatment to other parts of the vessel. Such migration could lead toserious complications, such as embolism, stroke, or a heart attack. Theuse of a vena cava filter has been employed to catch residual fragmentsthat have migrated from the site of a blood clot. In addition, somemechanical devices have utilized the concept of aspiration to establishor maintain a flow rate through a catheter for the removal of residualthrombus/fibrin material during treatment.

Therefore, there is a need to create a medical device in which theelements of the device used to clear an occlusion enhances the abilityof the device to effectively remove residual material or thrombusfragments from the vessel.

SUMMARY

The present invention generally provides a medical device for theremoval of a thrombus from a blood vessel. In one embodiment, themedical device comprises a tubular outer sheath having a first lumen anda second lumen; a wire guide disposed through the distal end of thefirst lumen for delivery of the device into the patient; an injectormechanism causing a lysin agent to flow through the second lumen; a wirebasket slidably received within the first lumen to generate a force thatmay cause further fragmentation of the partially lysed thrombus; and avacuum port coupled to the distal end of the second lumen for removinglysed thrombus fragments. The proximal ends of the first and secondlumen are positioned proximate to the thrombus with the device beingoperable in two modes, which include a first delivery mode and a secondmixing mode. In the first delivery mode, the basket is sized andextended proximate to the thrombus. In the second mixing mode, thebasket is caused to engage the thrombus to transmit force thereto in thefurtherance of lysing, fragmenting, and removing the thrombus.

In another aspect of the present invention, the lysin agent is anantibody selected as one from the group of streptokinase, urokinase,plasmin, alteplase, tenecteplase, reteplase, and a tissue plasminogenactivator. In addition, if desirable, the lysin agent may furthercomprise surface active polymers, emulsifying agents, anticoagulants, ora mixture thereof. The lysin agent may be delivered to the thrombus aspart of an isotonic or iso-osmotic solution.

In another aspect of the present invention, the wire basket is formedinto either an umbrella-shape or helical shape being comprised of atleast three wires. The wire basket may be coupled to a control memberthat can be used by an operator to manipulate the wire basket. The wirebasket is collapsible and can fit within a sheath or the first lumen ofthe medical device.

It is another objective of the present invention to provide a method ofremoving a thrombus from a blood vessel. This method comprises the stepsof introducing a sheath having a first lumen and a second lumen into ablood vessel; inserting a wire guide through the first lumen;positioning the proximal end of the first lumen and second lumenproximate to a thrombus; injecting a lysin agent into the blood vesselthrough the second lumen to at least partially lyse or dissolve thethrombus; delivering a cannula through the first lumen proximate to thethrombus; removing the wire guide from the first lumen; extending a wirebasket from the first lumen to a position proximate to the thrombus;causing the wire basket to translate back and forth to generate a force;transmitting the force from the basket to the thrombus to break thepartially lysed thrombus into smaller fragments; applying a vacuum tothe second lumen through the port positioned near the distal end of thefirst lumen; and removing the partially lysed thrombus fragments via theapplied vacuum.

In another aspect of the present invention, the method further comprisesthe step of securing the thrombus fragments proximate to the wire basketafter lysing and further fragmentation of the thrombus has occurred.

In yet another aspect of the present invention, the step of injecting alysin agent into the blood vessel enhances the blood flow in the narrowpassage ways in and around the thrombus and increases the ability of thelysin agent to be delivered to the thrombus. The lysin agent mayactivate fibrinolysis, thereby, affecting the cross-linking orpolymerization of fibrinogen and reducing the stability of the thrombus.

In yet another aspect of the present invention, the operator may controlthe wire basket relative to the sheath by manipulating it using acontrol member. The wire basket preferably has at least one of its wiresslidably receivable within a sheath and is collapsible within the sheathin order to be delivered proximate to the partially lysed thrombus.

In another aspect, in addition to removing lysed thrombus fragments, theapplication of a vacuum may also hold the lysed thrombus in a positionthat is proximate to the proximal end of the second and first lumen.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present invention in any way.

FIG. 1 is perspective view of a thrombectomy device in accordance withone embodiment of the present invention.

FIG. 2A is an enlarged view of the wire basket of the thrombectomydevice in accordance with one embodiment of the present invention.

FIG. 2B is an enlarged view of the wire basket of the thrombectomydevice in accordance with another embodiment of the present invention.

FIG. 3 is a schematic representation of a method for removing a thrombusfrom a vessel according to one embodiment of the present invention.

FIG. 4 is a schematic view of the distal portion of a thrombectomydevice engaged in the removal of a thrombus present in a vessel inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the present disclosure or its application or uses. Itshould be understood that throughout the description and drawings,corresponding reference numerals indicate like or corresponding partsand features.

The present invention provides a medical device useful for the removalof a thrombus from a blood vessel. Referring to FIG. 1, this medicaldevice 1 comprises a flexible tubular outer sheath 25 that encloses botha first lumen 15 and a second lumen 16 with each lumen having a distalportion 25B extending to a distal end 13 and a proximal portion 25Aextending from the distal portion 25B to a proximal end 12.

A wire guide (not shown) is placed through the proximal end 12 of thefirst lumen 15 to the distal end 13 of the first lumen 15 for deliveryinto the patient and positioning of the first and second lumensproximate to the thrombus. A lysin agent is injected through the secondlumen 16 to the thrombus. The wire guide is removed and a wire basket 10is extended through the distal end 12 of the first lumen 15 to aposition that is beyond the thrombus. The wire basket 10 is slidablyreceived by the first lumen 15 in order to generate and transmit a forceto the partially lysed thrombus that may assist in breaking it intosmaller fragments. A vacuum port 5 is coupled to the distal portion 25Aof the second lumen 16 for removal of thrombus fragments formed afterlysing and fragmentation of the thrombus has occurred. During theoperation of the thrombectomy device 1, the distal ends 13 of the first15 lumen and second 16 lumen are positioned proximate to the thrombus.

The wire guide arrangement in the first lumen 15 includes the use of ahollow needle (not shown) to pierce the patient's skin and enter thebody tissue at an angle with respect thereto. A wire guide 19 is theninserted into the hollow needle and is advanced percutaneously into thebody tissue to a desired position proximate to the occlusion in thevessel. The hollow needle is then pulled in a backward direction so asto be removed from the body tissue and from contact with the wire guide19. Next, the thrombectomy device 1 through its first lumen 15 isadvanced along the wire guide 19 to a desired position proximate to thethrombus.

A chemical lysin agent refers to any substance known to one skilled inthe art, including but not limited to enzymes and antibodies, thatsubjects a thrombus to a mechanism, such as lysis, cytolysis, orfibrinolysis, among others, which results in at least the partialdissolution, fragmentation, destruction, decomposition, or break-up ofsaid thrombus. Examples of an enzyme or antibody that may be used as alysin agent include, but not limited to streptokinase, urokinase,plasmin, alteplase, tenecteplase, reteplase, or a tissue plasminogenactivator. The lysin agent preferably activates fibrinolysis, whichaffects the cross-linking or polymerization of fibrinogen, therebyreducing the stability of a thrombus and resulting in its partialdissolution. The concentration of the chemical lysin agent used ispredetermined based upon the amount necessary to partially or fully lysethe size of the thrombus encountered. The chemical composition of thelysin agent may enhance the blood flow in the narrow passage ways in andaround the fibrin-thrombus obstruction, thereby, increasing the abilityof the lysin agent to be delivered to the thrombus. One skilled in theart will recognize that the lysin agent may further include effectiveconcentrations of surface active polymers, emulsifying agents,anticoagulants, and other additives useful in either increasing thesolubility of the lysin agent in water/blood, assisting in thedissolution of the thrombus, or inhibiting the re-growth of thethrombus.

Preferably the lysin agent is delivered as part of an isotonic oriso-osmotic solution, which is at the same or similar osmotic pressureas the blood within the obstructed vessel. Examples of solutions inwhich the lysin agent may be incorporated include saline, Ringer'ssolution, Krebs-Ringer's solution, and lactated Ringer's solution, amongothers. It should be understood that the lysin agent may also bedelivered in a solution that is not isotonic in nature.

Referring now to FIGS. 2A and 2B, the wire basket 10 may be formed bydistal portions of a plurality of multifilament wires 30 joined at afirst location 35 to a control member 40. It is feasible that thecontrol member 40 be formed by twisting the multifilament wires 30together or formed as a separate member, such as a rod. The controlmember 40 extends proximally through the first lumen. The wires may betwisted to be in contact with one another or joined by soldering,welding, use of metal bands, or clamps. It is feasible that the wiresmay form a second joint 36 at a distal tip that is shapedautraumatically to help prevent the occurrence of any damage to thevessel.

Preferably the wire basket 10 so formed is umbrella-shaped (FIG. 2A) orhelical shaped (FIG. 2B), although other shapes could be utilized. Thewire basket 10 is preferably comprised of at least three wires 30. Atleast one of the wires 30 and preferably all of the wires are slidablyreceivable within a sheath (not shown). The wires may have anycross-sectional shape known to one skilled in the art, with wedge-shapedor pie-shaped in its cross-section representing two examples. Each wirepreferably has a diameter of about 0.013 inches and may be comprised ofmulti-filaments with each filament having a cross-sectional diametersmaller than about 0.013 inches.

The wires may be composed of any medical grade material having theflexibility and strength necessary to be delivered to the obstructedsite within a vessel and used to break-up a partially lysed thrombusinto smaller fragments. Examples of appropriate medical grade materials,include, but are not limited to stainless steel and nitinol.

The wire basket 10 is preferably delivered through the second lumen 16of the medical device 1 using a delivery cannula or sheath (not shown).Manipulation of the control member 40 relative to the delivery sheathprovides the operator with control over the wire basket 10. The wireswhen collapsed inside a sheath or cannula assume an approximatelycylindrical shape in order to substantially fill the cross-sectionalarea of the sheath. Once the sheath and wire basket are delivered to aposition that is proximate to the partially lysed thrombus, the sheathis retracted or the control member further extended, resulting in thewire basket becoming exposed and allowed to expand to its desired shape.

It is another objective of the present invention to provide a method 2for removing a thrombus from a blood vessel. Referring now to FIG. 3,this method comprises the steps of introducing 100 a sheath having afirst lumen and a second lumen into a blood vessel; inserting 105 a wireguide through the first lumen; positioning 110 the proximal end of thefirst and second lumen proximate to a thrombus; injecting 115 a lysinagent through the 2^(nd) lumen to the thrombus to at least partiallylyse or dissolve the thrombus; delivering 120 a cannula through the1^(st) lumen; removing 125 the wire guide from the 1^(st) lumen;extending 130 a wire basket through the distal end of the cannula to aposition that is proximate to the thrombus; causing 135 the basket totranslate back and forth to generate a force; transmitting 140 the forcefrom the basket to the thrombus to break the partially lysed thrombusinto smaller fragments and to assist in lysing; applying a vacuum 145 tothe second lumen through a port positioned near the distal end of thesecond lumen; and removing 150 the residual material via the appliedvacuum.

The method of removing a thrombus from a blood vessel may furthercomprise the step of securing 140 the partially lysed and dissolvedthrombus fragments proximate to the wire basket prior to their removal150 by the vacuum. This optional step provides additional assurance thatthrombus fragments do not migrate away from the site of the treatment toother parts of the vessel where they may potentially lead to seriouscomplications, such as embolism, stroke, or a heart attack.

Referring now to FIG. 4, an example in which the distal portion 25B of athrombectomy device engaged in an interaction with a thrombus 45 locatedwithin a blood vessel 50 is depicted. A wire guide is used to bring thefirst 15 and second 16 lumen near or proximate to the thrombus 45. Lysin55 is injected through the first lumen 15 to at least partially lyse thethrombus 45. A wire basket 10 is then extended through a sheath (notshown) from the second lumen 16 via manipulation using a control member40. Translation of the wire basket 10 back and forth generates a forcethat is transmitted to the thrombus 45, thereby, facilitating breakingthe partially lysed thrombus into smaller fragments 65. A vacuum 60applied through the first lumen 15 assists in the removal of thepartially lysed thrombus fragments 65.

In addition to removing partially lysed thrombus fragments, theapplication of a vacuum 60 may also hold the thrombus 45 in a positionat the proximal end of the proximal portion of the second lumen 16,which may effectively assist the chemical dissolution and mechanicalfragmentation process.

A person skilled in the art will recognize from the previous descriptionthat modifications and changes can be made to the present disclosurewithout departing from the scope of the disclosure as defined in thefollowing claims.

1. A method of partially lysing and removing a thrombus from a bloodvessel, the method comprising the steps of: introducing a sheath havinga first lumen and a second lumen into a blood vessel; inserting a wireguide through the first lumen; positioning the proximal end of the firstlumen and second lumen proximate to a thrombus; injecting a lysin agentinto the blood vessel through the second lumen to at least partiallylyse the thrombus; delivering a cannula through the first lumenproximate to the thrombus; removing the wire guide from the first lumen;extending a wire basket from the first lumen to a position proximate tothe thrombus; causing the wire basket to translate back and forth togenerate a force; transmitting the force from the basket to the thrombusto break the partially lysed thrombus into smaller fragments; applying avacuum to the second lumen through a port positioned near the distal endof the first lumen; and removing the partially lysed thrombus fragmentsvia the applied vacuum.
 2. The method of claim 1, wherein the methodfurther comprises the step of securing the thrombus fragments proximateto the wire basket after lysing and break-up of the thrombus hasoccurred.
 3. The method of claim 1, wherein the step of injecting alysin agent into the blood vessel enhances the blood flow in the narrowpassage ways in and around the thrombus and increases the ability of thelysin agent to be delivered to the thrombus.
 4. The method of claim 1,wherein the step of injecting a lysin agent into the blood vesselactivates fibrinolysis that affects the cross-linking or polymerizationof fibrinogen and reduces the stability of the thrombus.
 5. The methodof claim 1, wherein the step of extending a wire basket the operatorcontrols the wire basket relative to the sheath by manipulating acontrol member.
 6. The method of claim 5, wherein the wire basket has atleast one of its wires slidably receivable within a sheath.
 7. Themethod of claim 6, wherein the wires are collapsible within the sheathin order to be delivered proximate to the partially lysed thrombus. 8.The method of claim 1, wherein the step of applying a vacuum furthercomprises holding the lysed thrombus in a position that is proximate tothe proximal end of the second lumen.
 9. A medical device to partiallylyse and remove a thrombus from a blood vessel, the device comprising: atubular outer sheath having a first lumen and a second lumen with eachlumen having a distal portion extending to a distal end and a proximalportion extending from the distal portion to a proximal end; a wireguide placed into the proximal end of the first lumen for delivery to apatient through the proximal end of the first lumen, an injectormechanism causing a lysin agent to flow through the second lumen; and awire basket slidably received within the first lumen to replace the wireguide; a vacuum applied through the second lumen to remove the at leastpartially lysed thrombus; the device being operable in two modesincluding a first delivery mode and a second mixing mode; wherein thebasket is sized and extended proximate to the thrombus in said deliverymode; wherein the basket is caused to engage the thrombus to transmitforce thereto in the furtherance of at least partially lysing andremoving the thrombus in said mixing mode.
 10. The device of claim 9,wherein the lysin agent is an antibody selected as one from the group ofstreptokinase, urokinase, plasmin, alteplase, tenecteplase, reteplase,and a tissue plasminogen activator.
 11. The device of claim 9, whereinthe lysin agent further comprises surface active polymers, emulsifyingagents, anticoagulants, or a mixture thereof.
 12. The device of claim 9,wherein the lysin agent is delivered as part of an isotonic oriso-osmotic solution.
 13. The device of claim 12, wherein the isotonicsolution is one selected from the group of saline, Ringer's solution,Krebs-Ringer's solution, and lactated Ringer's solution.
 14. The deviceof claim 9, wherein the wire basket is formed into either anumbrella-shape or helical shape.
 15. The device of claim 9, wherein thewire basket is comprised of at least three wires.
 16. The device ofclaim 9, wherein the wire basket is coupled to a control member that maybe used by an operator to manipulate the wire basket.
 17. The device ofclaim 9, wherein the wire basket is collapsible and fits within a sheathor the first lumen.